Options accepted by I18n.toSentence.
Joins the last two words of a longer list (e.g. ", and ").
", and "
Joins the words when the list has exactly two items (e.g. " and ").
" and "
Joins all words except the last two, e.g. the ", " in "a, b, and c".
", "
"a, b, and c"
Options accepted by I18n.toSentence.